A vaporizer is a device which heats up dried herbs to a temperature at which they release their (medically) active components into an aromatic vapour. This vapour doesn't contain any of the toxic elements found in smoke.

Not all vaporizers are suited for heating liquids, but there are some (for example the Aromed 4.0 and the Volcano vaporizer) which provide extra parts that allow one to vaporize oils and tinctures.

When medicinal plants are vaporized and inhaled, this process is generally referred to as phyto-inhalation rather than aromatherapy. An extensive list of herbs that can be vaporized can be found in this vaporizing temperatures table.

A vaporizer might be expensive because of the materials used (borosilicate glass, metal, heat resistant plastic etc.), the technique employed (type of heating element, analogue or digital temperature control etc.) or both. A good vaporizer doesn't have to be expensive, and an expensive vaporizer isn't necessarily better. But if you're looking for a device that lasts long and can be used comfortably, buying one of the cheapest vaporizers will likely be disappointing.

If you already have a (small) glass bong or an iron pipe, you can easily transform it into a vaporizer with the Vaporstar or the Vapo-bowl respectively. It's also possible to make a very simple vaporizer from a light bulb, or even to make a whip convection vaporizer, although the latter especially may not be very safe. We do not recommend building your own vaporizer with a heat gun (like a hot air paint stripper), because such heat sources were made for industrial purposes, not for inhalation.

Generally not, but this depends on the type of vaporizer. For some models emptying and refilling the herb chamber or cleaning the vaporizer might be a bit bothersome. One must always be careful, as the heating element and the filling chamber can get very (very!) hot.

It is likely that you're vaporizing at a temperature too high. Though it can be nice to inhale very concentrated white vapour (because of the strong effect), it is difficult to keep this in the lungs. Lower the temperature and the coughing will likely cease.